Grinding machine



R. A. HEALD- ET AL GRINDING MACHINE Filed Feb. 19, 1927 6 Sheets-Sheet 1 -WaEcLo 3. Guild Oct. 2, 1928. 1,686,275

R. A. HEALD ETIAL GRINDING MACHINE Filed Feb 19, 1927 e Sheets-sheet 5 I91 I I88 9 [80 130 133 I34 190 135 57 9 Richard H. mam WaEdo ZLGu'LBd,

- R. A. HEALD ET AL GRINDING MACHINE Filed Feb. 19, 1927 6 Sheets-Sheet 4- Wm Richard A. HcaPcL 35 WqPdO 3. Guild,

Oct. 2, 1928.

R. A. HEALD. ET L GRINDING MACHINE 6 Sheets-Sheet 5 Filed Feb. 19, 1927 fl w RLchard, H. HqPd WqPclo 8. Guild Oct. 2,1928.

R. A. HEALD ET AL I GRINDING MACHINE Filed Feb. 19, 1927 6 Sheets-Sheet 6 mm W w F 5 w L a K MOW a M Illlllllllll Patented (let. 2, 1928.

warren, stares News raranr caries.

RICHARD A. HEALD AND WALDO J. GUILD, 0F WORCESTER, MASSACHUSETTS, AS- SIGNOBS TO THE HEALD MACHINE COMPANY, OF WORCESTER, MASSACHUSETTS.

A CORPORATION OFMASSACHUSETTS.

GRINDING MACHINE.

. Application filed February 19, 1927. Serial No. 169,510.

The invention relates to multi-spindle grinding machines adapted to simultaneously grind a plurality of holes to a given uniform and predetermined diameter. The machine of the invention is particularly adapted for simultaneous grinding of the cylinder bores in thecylinder block of internal combustion engines.

The object of the invention is to make grinder of the above character entirely automatic in itsaction. so that, once started, the several internal cylindrical surfaces will be brought to a uniform and exact size,- whereupon the grinding will automatically cease. The machine of theinvention accomplishes this, as will hereinafter appear, without the use of any caliper levers, sometimes called feelers. As shown, the automatic features of the invention are applied to that type-of cylinder grinder in which the grinding wheels, mounted on spindles, partake only of reciprocating motion, along the axes of said spindles, while the workpiece, as represented for example, by the cylinder block above specified, partakes of an-ec'centric inotion. That is to say, every particle of the workpiece moves in. acircle, the radius of which is termed herein the radius of eccentricity, and all particles ofsaid workpiece move in a circle of equal radius; from which it follows that a line drawn through any two given points on the workpiece will never change its-direction, although it changes its position.

Another object which our invention accomplishes is the truing or dressing of the grinding wheels, thus to keep them sharp and free cutting. This operation also takes place automatically.

In order todress or true the grinding wheels, the several spindles upon which they are mounted are moved upwardly to carry the wheels out of the workpiece and past a plurality of dressing devices, preferably diamonds; Subsequently, the regular grinding traverse is resumed and when the holes have been brought to finished size, the spindles all move upwardly again, moving the grinding wheels past the nowinoperative dressing devices, the head upon which said spindles are mounted finally comingto a stop so that the operator may remove the finished block.

We do not claim per se the eccentric ac. tuating mechanisl land feed herein dc.

scribed, and it will therefore be understood that we are not limited to this particular kind of grinder, but the various automatic controls and dressing mechanisms could be applied to that type of cylinder grinder in which the grinding wheel and spindle par take of an orbital motion. The machine disclosed in the accompanying drawings makes use of the prior invention of Waldo J. Guild as disclosed in United States Letters Patent No. 1,682,672, granted August 28, 1928, and also makes 'use of certain other prior inventions that are referred to in the said patent.

The above will more fully appear in the following description taken in connection with the accompanying drawings, in which- Fig. 1 is a side elevation of a grinding machine constructed in accordance with our invention.

Fig. 2 is a view, partly in section and partly in front elevation,- the section being taken on the line 2-2 of Fig. 1.

Fig. 3iis an enlarged sectional view on the line 3-3 of Fig. 2.

Fig. 4 is an end elevation of the diamond actuating slide.

Fig. 5 is a sectional view onthe line 5--5 Fig. 9 is a. sectional view of the main reversing valve mechanism, together with" a diagrammatic representation of the fluid pressure. system.

- Fig. 10 is an isometric drawing of the com pensating mechanlsm.

Fig. 11 1s a' sectional view on the line .11-11 of Fig. 2.

Fig. 12 is a view on an enlarged scale of the reversing dogsfor the wheel head.

Fig. 13 is a fragmentary plan view showing an adjustment device for a wheel head dog. i

Fig. 14-is a sectional view, showing a modification of the invention.

Fig. 15, also illustrating said modification, is a view of an automatic belt shitter.

drivin Like reference characters refer to like parts in the different figures.

Referring first to Figs. 1 and 2, the machine is built on a base 1, from which extends upwardly a wheel head support 2. The latter provides vertical slideways 3 for the vertical reciprocation of the wheel head 4; it will be understood, however, that the grinding wheels could be maintained stationary and the reciprocatory motion given to. the work holding table 5; in any event, the said reciprocation is utilized to produce a relative traversing movement between the grinding wheels 6 and the Work. The grinding wheels 6 are mounted on spindles 7 which are rotatably carried in journals in the head 4,v electric motors 8 being provided to rotate said spindles and grinding wheels. The manner-and means for mounting and driving spindles being well known and no part of our present invention, such will not be further-described, and it is noted that any other drive or mounting could be substituted for that shown.

The reciprocation of the head 4 to cause the rotating grinding wheels 6 to make the required interior traverse of the workpiece, for example, the cylinder block 9 for an internal combustion engine, may be imparted in any well known manner, as. for instance, by theme of the fluid pressure controlling and reversing mechanism described in United States Letters Patent No. 1,582,468, to James N. Heald and 'one of us, viz, Guild,

granted 'April'27, 1926. At all events, the means employed for the reciproca tion 0 the head 4, be it hydraulic drive. gear drive, or any other type,'pr0cures the reversal of said head at each end of its normal working stroke by the use of spaced adjustable dogs 10 and 11, carried by the head 4 and adapted to alternately engage and move a reversing member 12; said member 12,

the workpiece 9, is situated between the two I duringthe grinding operation, when the wheels 6 are moving back and forth within dogs 10 and 11 inposition to be struck alternately by said dogs, and'said member 12, by its consequent movements, first in one way and then the other, effects the reversals in the travel of thehead 4.

- Briefly, as shown in Figs. 1 and 9, the reversing member 12 is connected to a valve member 13 which controls admission of the pressure fluid supplied, for example, by a pump 14 to the upper or the lower end of a cylinder 15in which is located a piston 16 having a piston rod 17 which is attached to the head 4, as clearly shown in F ig. 1. The valve ports leading to the lower and upper end of the cylinder 15 are indicated by the numerals 18 and 19-. respectively, while the fluid entrance port is numbered 20 and the exit port 21. It will be noted that the area of the piston rod 17 must be subtracted from the area of the piston 16 to obtain the effective pressure for the down stroke of the head 4, and in this manner the weight of the head 4 is at least partially compensated for.

The work holding table 5 may be actuated from any suitable source of power. As 1ndicated in Fig. 1, a tight and loose pulley 23 WVOIITI wheel 27 which is keyed or otherwise fastened to a hollow upright shaft 28 provide'd with an enlarged head 29. Inside the shaft 28 is another shaft 30, and these two shafts rotate together at the same speed, eX-

cept when the eccentricit is being increased or decreased, as will presently appear.

The hollow shaft 28 is driven directly from the worm wheel 27, as clearly indicated; the shaft 30 is actuated at equal speed in the following manner. A bevel gear 31 is attached to or, if desired, integral with the worm wheel 27 A bevel gear 32 of the same size as gear 31 and coaxial with it, but facing in the opposite direction, is fastened to anystationary part of the base 1. Stationary gear 32 provides a journal for a bevel ear member 33, which in turn serves as the bottom bearing for the shaft 30. Gear member 33 is stationary, except when the eccentricity of the table 22 is being changed. As the stationary gear 32 is duplicated by the gear 31 on shaft 28, so the normally stationary gear 33 is duplicated by a bevel gear 34 fastened to the shaft 30.

Loosely mounted on the said shaft 30 be.- tween the gears 33 and 34. is a member 35. This member provides studs 36 and 37 on which are rotatably mounted bevel gears 38 and 39, respectively. The gear 38 isthe larger of the two and meshes with the bevel gears 31 and 32; the gear 39 meshes with gears 33 and 34.

Since the gear'32 is always stationary and the gear 33 is normally so, these gears are in effect tracks (the latter being movable), on which the bevel gears 38 and 39 revolve.

The former is driven directly from gear 31,

' but if and'when either of the track gears 32 or 33 are moved, the shaft 30 will be given ,a movement relative to the shaft 28.

i stated, we choose to fasten the gear 32 to the frame of the machine, and consequently this movement of the shaft 30 relative to the shaft 28, which is a feeding movement to inpins crease or decrease the eccentricity, is effected by rotation of the gear member 33.

Before describing the automatic feed mechanism which actuates the gear 33, we will explain how rotation of the shaft 28 and head 29 gives the table 22 its eccentric motion.

The head 29 carries a lug 40 which provides a journal or hearing for a screw shaft 41. The latter is received in a threaded lug 42 which extends downwardly from a member 43, which is mounted to slide radially onways 44 provided by the head 29. See in this connection Fig. 11. The slide member 43 therefore partakes of the rotation of the head 29. On the upper side of the slide member 43 is a turret 43" which holds one race of a ball bearing 45. The table 5 is attached to the other race of said ball bean %)n the top of the shaft 30 is a bevel gear 46. Thismeshes'with a bevel gear 47 on the screw shaft 41. When the shafts 28 and 30 rotate together as they normally-do, gear 46 can have no effect on gear 47, but when the shaft 30 is moved relative to the shaft 28, gear 46 will turn gear 47 and thus, by means of the screw shaft 41 and threaded lug 42, the slide member 43 will be moved.

Assuming .that the turret is concentric with shaft 28 and head 29, it is obvious that table 5 will not be moved by rotation of shaft 28. When the slide member 43 is moved to carry the turret away from the center some part of the table 5-must evidently move in a circle, and the radius of that .circle will be equal to the eccentricity of the turret 43 on the rotating head 29. Consequently, this distance is called the radius of eccentricity. I

In order to keep the table always correctly oriented, so that all parts of it will move in equal circles, with any line thereof always parallel to a given line on the base of the machine, we provide a parallel motion as follows :-As best shown in Fig. 6, the base 1 of the machine provides a pair of pins 48 and 49. Pivotally mounted on these pins area pair of identical bars 50 and 51. A link 52 connects the opposite ends of said bars,

53 and 54 being provided for this purpose, and the length of this link 52 (between the pins 53 and 54) is the same as the distance between the stationary pins 48 and 49. Bars 55 and 56 of equal length are also attached to the pins 53 and 54, and the other ends of said bars connect to the table 22 at pins 57 and 58, the distance between which is-the aforesaid established distance between pins 48 and 49, or between pins 53. and 54. This mechanism constitutes a parallel mo tion. and allows the table 5to move, as a whole, a limited distance in any direction, but maintains the line through pins 57 and 58 always parallel to the line of pins 48 and Referring again to Fig. 2, the'gear memher 33 which, as aforesald, 1S movable to change the radius of eccentricity, extends through the bearing provided by the gear member 32, a large spur gear 59 being fastened to it on the other side. A. pinion 6O meshes with the gear 59, said pinion being on the bottom of a vertical shaft 61 supported in journals 62 and'63 provided by the base 1. On the top of the shaft 61 is a bevel-gear 64 provided by an horizontal shaft 66. The shaft 66 is controlled and actuated by the automatic means to change the radius of eccentricity, hereinafter termed the feeding inechanismfand by the compensating mechanism which compensates for reduction of the grinding wheel, due either to wear or dressing, or both.

The feeding and compensating mechanism is shown in section in Fig. 2, but a better understanding of it may be had from the enlarged sectional View of Fig. 7. Referring to said figure, rotation of the shaft 66 in a clockwise direction, as viewed from the right hand end of Fig. 7 (in this particular embodiment of the invention) is adapted to increase the radius of eccentricity. At this point, it may as well be noted that the increasing of said radius causes the workpiece to be enlarged internally, the radius of the hole being at any moment of grinding equal to the radius of the grinding wheel at that moment plus the radius of eccentricity.

The shaft 66 is adapted to be rotated manually by means of a hand wheel 67 and mechanically from a ratchet'wheel 68, the

latter being automatically given a step-bystep movement, as Will hereinafter appear. Ratchet wheel 68 is directly fastened to an annular piece 67 which is herein shown as Y formed integrally with the hand wheel 67. Fastened to the piece 67 is a stud 69, which rotatably carries a pair of gears 70 and 71 formed out of a single iece.

Keyed or otherwise astened to the shaft 66 is a sleeve 72. This sleeve provides a convenient bearing for the annular piece 67 and it also provides a gear portion 72*:which meshes with the gear 70. Another sleeve 73 surrounds the shaft 66, but is not fastened thereto. .This sleeve has a gear portion 7 3 which meshes with the gear 71.

Considering, for the moment, that the sleeve73 is stationary, it will be apparent that rotation of the elements 67, 67 and 68 very much reduced speed, since the gears 70 and 71 differ slightly, and only slightly, in diameter. i

A ring 74 is carried by the element 67*. This ring 74 desirably has suitable scale markings, not shown, on its periphery.

Preferably this ringis adjustable on the member 67 and to this end a binding screw,

not shown, holds it in any desired position of adjustment. On the ring 74 is a cam projection 76, indicated in dotted lines F ig. 1, and diagrammatically in Fig. 8, one end i of it being shown in section in Fig. 7. A

pair of contactterminals is likewise shown in section 1n said Fig. 7; the machine providesanother pair (as. shown in Fig. 1).

whichare identical in construction, so one description will serve for both. As shown, thumb screws 77 and 78 (see Fig. 1 for both) are carried by rock levers 7 9 (revertingto Fig. 7 pivoted at 80. Terminals81'are carried by the levers 79, and when the cam 76,

by engagement with'the screw 7 or 78 moves a rock lever upwardly, the terminal in quesaround the reduced portions tion, 81, engages a terminal 82.; The latter are mounted on the frontof plungers 83, which are slidably held bycylindrical members 84 of insulating material. The plungers have reduced portions 85, which extend through the insulating material and are threaded at the rear end. Springs 86 fit v 85. The threaded parts of the portions 85 serve as binding posts, nuts 87, 87 being provided for the attachment of wires, and at the same time to allow the plungers 83 to be pressed into a given'position by the springs 86. The above construction allows a firm contact to be made, using heavy rock levers 79 for accuracy, yet without danger o f breaking any the head 4 carries a bar 88 by means of which the table parts.

Referring now. to Fig. 1,

dogs 10 and 11 are adjustably carried, as will be more particularly pointed out hereinafter. This bar 88 also adjustably carries acam member'89 bymeans of which the l ratchet 68 is actuated. As shown in Fig. 1, 'and also in the isometric view of Fig. 10,

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a lever 90, pivotally mounted at 91 on the wheel head support 2,'carries a roller 92 at one end. This roller is in the path of the cam 89, and said cam is so adjusted on the bar 88 that-it will strike and move the roller 92 and lever 90 once during each grinding reciprocation of the head 4-. A link 93 connects the other end of lever 90 to a lever 94 pivotally mounted .at95 on the base 1. The lever 94 carries a spring pressed operating pawl 96 adapted to actuate the ratchet 68. A stationary shield 97 is provided for awl from the the purpose of'lifting the rom each sucratc'het teeth at the return cessive actuation so that the hand wheel 67 is free to be turned manually. At the end of each actuation, the parts above described are returned to the initial position, with the I lever 90 against a stop 98, by means of a spring 99.

and 82 In this connectlon, Fi .1 should be observed, remembering that t e step-bystepmovement of the cam 76 is clockwise;

also Fig. 8, which shows the operative relation (not the construction) of the parts. VVhe'n the terminals 81 and 82 make contact, an electrical circuit is closed which, by the mechanism presently to be described, causes the head 4 to move upwardly, drawing the grinding wheels 6 out'of the workpiece, and simultaneously causes wheel dressing devices 100 to move into .the amplified path of said wheels 6, thereby to dress and true them all.

As shown by the wiring diagram of Fig. 8, electric current may be supplied by a. generator G, driven continuously by any suitable means, not'shown, from some suitable source of power, for example, the shaft 25.

One terminal of this generator is grounded as shown at 101, and the other is connected by a supply wire 102 to the central bar or plate 103 of a two way switch, the movable member 10401? the latter being mounted on a box orcasing member 105 disposed as shown in'Fig. -1 on the wheel head support 2. Said switch provides additional contact plates or bars 106 and 107, arranged on opposite sides of the central bar 103 and adapted to be alternately connected electrically to said central bar .103 b aconnector 108, which is carried by the a ore'mentioned switch member 104. Said switch member is pivoted at 109 and in its normal position as shown, Figs. 1 and 8, disposes the connector 108 in-contact'withand across the two plates 103 and 106; in the other position of the member 104 the connector 108 connectsthe two plates 103 and 107.

' When the grinding wheels 6 are taking the preliminary cuts on a workpiece 9, the switch member 104 occupies said normal position of Figs. 1 and 8, and underthese conditions the supply wire 102 from the generator G is connected to a wire '110 running from the plate of bar 106 of the switch. Said wire 110 runs to the coil of an electromagnet 111,

desirably located in the aforesaid box or casing 105; A return wire 112 from the coil of the electromagnet 111 is connected to the contact terminal 82.

When the terminals 81 and 82 are brought together as above described, by the action of cam 26, the circuit through electromagnet 111 is completed, since the terminal 81- is grounded as shown at 113, Fig. 8. This energizes the electromagnet 111, causing attraction of an armature member 114, and the consequent elevation of its attached lever arm 115, these parts being pivoted at 116 in the casing 105. Such movement of the lever arm 115, responsive to the engagement.

final and finishing cuts taken by said wheels to bring the several holes in the workpiece to the desired size. This involves .the withdrawal of the grinding wheels 6 from the workpiece, and the disposal, in their temporarily amplified path of movement, of

' dressing devices or diamonds 100; these two operations are effected through themedium of the lever arm 115 in the ner:

. Referring to Fig. 1, the lever arm 115 has a downward extension 117 which is slidably connected to a valve member 118. The latteris best shown in the fluid pressure diagram of Fig. 9, and as shown in said figure, the valve member is adapted to connect. piping 119 shunted into the main pressure piping 120 to diamond operating piping 121. To that end, a valve casing 122 in which the valve 118 located provides three ports 123,' 124 and 125 which ollowing manare in order a fluid entrance port 123, a

fluid exit port 124 connecting to the piping 121, and a discharge port 125. When the valve member is in the position shown in Fig. 9, which it assumes prior to the energization of magnet 111, pressure fluid cannot go through the valve; on the contrary,

. the piping 121, which leads'to the diamond controlling mechanism, is in direct connection with the discharge port 125, allowing the fluid tos. be discharged into the main tank, not shown, which is usually provided in grinding machines of this character. When, however, the valve 119 is moved, as above set forth, a reduced portion 126 on said valve 118 allows the pressure fiuidto enter the'piping 1'21 and at the same time the exhaust port 125 is closed. Y

vThepipin 121'leads'to a port 127 in a hollow cylin er 128 provided by a member 129 which is connected to the support 2 in a manner which,will be presently Still referring'to Fig. 9, the cylinder 128 has escribed.

a piston 130 on the end of a plunger 131. The plunger extends into a chamber 132 into which projects a pin 133 carried by a movable diamond slide 134. vOn the other side of the pin 133 is a spring 135, which is adapted to return the parts to initial posi- 'tion as soon as the pressure is relieved.

The slide 134, as best shown in Figs. 3 and 4, is mounted to slide in ways 136 on the member 129. Said slide provides a pluralit'y of lugs 137, (as many lugsas there are grinding wheels 6), each of which receives the usual threaded nib 138 on the front of which are the diamonds 100. It is obvious that when the valve member 118 is moved and the pressure fluid is admitted to the cylinder 128, the slide 134 will be moved to the right, Fig. 3, carrying the several diamonds 100 to the dotted line position of Fig. 3.

As before stated, the other operation inaugurated by engagement of terminals 81 and 82 is the automatic amplification of the reciprocatory path of the head 4 to carry the wheels 6 past the dressing diamonds 100. As shown in Fig. 1 and on an enlarged scale in Fig. 12, the lower dog 11, which limits the upward movement of the head 4, is

.carried by a block 139 which, instead of being secured directly to the bar 88, as is the case with the block 140 of dog 10, is mounted slidably on said bar, Under normal conditions, when the head is making its usual working reciprocation to traverse the wheels 6 back and forth within the workpiece, the block 139 of dog 11 is held in definite spaced relation to a block 141', which latter, the same as block 140 of upper dog 10 is a stationary block, adapted to maintain its predetermined setting or adjustment vertically on the head 4, as given it by any suitable adjustment or holding devices, such -for instance. as the thumb screws 142-142 applied to both blocks 140 and 141 and engaging with the bar 88.

The device employed to hold the slidable block 139 in spaced relation to the fixed block 141 is here shown as a latch lever 143 which has a spring 144 engaging it and which is pivoted at 145 on block 141. The upper free'end'of the latch lever'143 is in abutting relation toa shoulder 146 on block 139, thereby holding the block 139 at a predetermined distance above the block 141. The lever arm 115 is in position to engage the latch lever 143, and when it does, moving .said latch lever 143,. to the left Fig. 12, the normal connection between the slidable block 139 and the fixed block 141 is broken, and when this occurs on the upward movement of the head 4, the block .139 falls, and the dog 11 does not shift the reversin member 12. Thus the upward movement 0 the head 4 on -this particular stroke will be extended latter, asalready described, have been moved into operative position as the upward movement of the head 4 begins.

. The block 139 when freed in the manner above described, does not at once descend all the way to the point where it, or an adjustment screw 147 provided by it, would strike the block 141; but said block is caught, after descending a limited distance, by a spring-pressed member 148. Said member 148, pivotally mounted on the support 2, has a pair of inclined surfaces 149 and 150 for cooperation with inclined surfaces 151 and 152 at the right hand corners of the block 139. In the normal. grinding operation of the machine, when the blocks 139 .and 141 are connected by latch 143, the inclined surfaces on member 148, although in the path of block 139,0lfer no effective obstruction to the back and forth travel of said block in unison with the head 4, but when the block 139 is freed from the block 141, as above described, the member 148 holds said block stationary. The head .4 continues to ascend, until the block 141 strikes the adjustment screw 147, whereupon the block 139 is lifted, and the dog 11 is thereby moved against the reversing member '12 to shift it ,over, thus reversing the travel of the head at the end of its amplified stroke; thereupon the block again drops against the member 148 and thereby is held from further downward movement. The head 4 now descends carrying downward the block 141, whereupon the latchmember 143 again takes its place behind the shoulder 146 andthe parts are then-restored to normal position.

, On this amplified upward dressing stroke of the head4, an arm-153 pivoted at'.145 which is connected by a spring 154 to another arm 155 whereby both arms tend to assume the position shown in Figs. '1 and 12 strikes an arm 156 of the switch -member 104, thereby rocking the connector 108 of saidswitch away from bar 106 (see Fig. 8) which prevents a repetition of the dressin stroke. Thereupon theconnector 108 is isposed in position where it connects the switch plates or bars 103 and 107. On

the dressing stroke, arm 155 does not pass over a second projection 157 of switch member 104 as the stroke is not long enough. On the return stroke arm 153 passes over projection 156. A wire 158 runs from the switch bar 107 to the coil of a second electromagnet 159, and the other endof said coil is connected by a .Wire 160 to the contact 82.

After the wheel dressing operation above described, and with the resumptionof grindin'g upon the several hollow cylinders in the workpiece, the feeding motion to increase the radius of eccentricity .involves further clockwise rotation of the ring 74, which ultimately carries the cam 76 into engagement with the screw 78. The parts by the lever 165,

are 'so set and adjusted that the engagement the electrical circuit through the magnet159,

since the contact 81 is grounded the same as the contact 81 at 113. Thus the electromagnet 159 is energized, causing the attraction of an armature member 161 plvoteu on the same spindle 116 which forms the pivot for the armature member 114, the magnet 159 being directly behind the magnet 111. The armature 161 provides a lever arm 162 for cooperation with thelower dog 11in the following manner Said reversing dog 11, ,as shown in Fig. 12, ispivoted at 163 to its carrying block 139, and normally is pressed by a flat spring 164 in the position shown in Fig. 12, with the free end of said dog in position to engage and move the. reversing member 12 at the end of the upward normal working stroke of the head 4. When the lever arm 162 is raised into the path of dog 11, the latter, on the upward movement of the head 4, by, reason of its pivotal mounting, is free to ride on the inclined-surface of said lever arm; thus the striking end of said dog is carried clear of the reversing member 12 and e the head 4 continues its movement upward,

carrying the grinding wheels 6 out of the tween the fluid port 18, which leads fluid tothe bottom of the cylinder 15 and the fluid carrying piping 167, and, as shown in Fig. 9, normally allows the fluid to flow past it,

being held open by a strong spring 168.

The latter seats against the end of a rod 169, and when this rod is forced downwardly crushed (the valve member 166 being loosely fitted on the rod) and the combined action of a. weak spring 170 and the'force of the fluid closes the valve. Thus, by blocking the flow of fluid to the bottom of the cylinder 15, the head 4 is brought to a stop, and it will be noted that when the reversing valve 13 is manually moved to start the head 4 down again, the valve 166 will be forced upwardly by theback-flow offluid through pipe 167 as the piston in cylinder 15 is forced down.

It will be noted from the foregoing description that the grinding of the work piece has been done in two stages,first a rough grinding, the completion of which is determined by the engagement of contacts- 81 and 82 due to the action of cam 76 on the strong spring 168 is adjusting screw 77. By the action of the electrical circuit thus completed, the wheels 6 are withdrawn from the workpiece and submitted to a dressing by the dressing diamonds 100. The resurfaced and sharp wheels reenter the holes in the workpiece and grinding is continued until the contacts 81 and 82 are brought together by the action of the said cam 76 on adjusting screw 78, at which time the wheels are withdrawn to rest position, clear of. the workpiece, by the action of the electrical circuit thus completed. This last stage of grinding subsequent to the dressing operation is of fixed duration, being controlled by the number of feeding increments imposed uponratchet disk 68 necessary to carry the cam 76 from the point wherecontacts 81 and 82 are first engaged up to the point where contacts 81 and 82 are brought into engagement.

If the increments -of advancement of ratchet 68 and the resulting increments of increase in the eccentricity of workpiece are so controlled that during this stage of grinding, the wheels cut away the material as rapidly as the same is fed to the wheels, then ,it can be truthfully said that the radius of the workpiece at any time during this stage will be the original radius of the wheel at the commencement of this stage plus the eccentricity radius wear of the wheel durin such a short stage of grinding is inappreoizfble. It is also true, regardlessof the condition of the holes in the workpiece at the beginning of the stage, as the wheel is dressed off enough to allow the wheel to-reenter the hole with practically no cutting action, even under the most adverse rough grinding conditions which would have resulted in-a smaller hole at the beginning of this finish grinding stage.

It will therefore be seen that the diamond' dressing tools may be made sizing devices by' so controlling these diamonds that at the start of this finishing stage the size of the wheels generatedby the dressing operation will bear a fixed relation to the radius of eccentricity of the work at this time, so that the fixed lncrease of eccentricity from this point on will result in bringing the workpiece to a predetermined. size.

However, the radius of the wheel must decrease with each dressing operation and the dressing diamonds must of necessity be advanced toward theplan e of the wheels at some time betweendressing operations so that they may be "in position to sufficiently decrease the radius of the wheels both to sharpen the wheels and to allow the same to reenter the holes without appreciable cutting action. If no other compensation were made, this reduction of the wheel'radius by dressing in the cycle of grinding of each workpiece would result in a corresponding reduction in the finished size of succeeding This is true because the workpieces, since at the completion of each cycle of grinding (at the engagement of contacts 81 and 82) the radius. of eccentricity would be duplicated and therefore thesim of the radius of eccentricity and the wheel radius, which is the measure of the resulting-work radius, would be decreased by the same amount as the wheel radius is de- 1 creased. Therefore a compensation must be made in the mechanism which controls the radius of eccentricity, so that, at any given point in the cycle of grinding of one workpiece, the radius of eccentricity shall have been increased over the radius at the corresponding point in the cycle of the last proceeding workpiece; the amount of this increase in radius of eccentricity being equal to the amount of the reduction in wheel radius and, therefore, also equal to the amount by which the diamond tools are advanced between succeeding dressing operations.

. As a result of such compensation in equality with the diamond advance. the sum of the radius of the wheel and the radius of the work eccentricity, at the time when contact points 81 and 82 areengaged, will be maintained constant on successive workpieces and said workpieces will be ground to uniform size.

The use of upward travel of the wheel carrying head/1 to provide this compensation and also the means for advancing the operative positions of the diamond toolsv Will now be described.

Turning now to Figs. 1 and 10, the bar 88 carries a pin 171 which when head 4. moves upwardly to its highest position as described, engages an arm 172'pivoted at 173 on the head support 2, and by engagement of a lug 17 1 with a set screw 175 moves ,a lever 176, pivoted on the same stud 173 lever carries a spring pressed pawl 183 adapted to engage with, and move a'ratchet wheel 184: WhlCl'l is keyed to the sleeve 7 3 on which is formed the gear 7 3, as shown in Fig. 7. Movement of this ratchet wheel 18 1 serves to increase the value of the radius and diameter of eccentricity at that time when the contacts 81 and 82 are brought together during, the grinding of the next succeeding workpiece, and'this is so for the following reason :'the gearings 70, 71. 72 and 73 constitutes a differential mechanism from the fact that the axis of gears 70 and 71. is movable with the hand wheel 67, said axis being represented by the stud 69. Thus it .will be seen that movement of the element comprising theparts 68,67, 67 a and 69 results in feeding movement of the shaft 66,

ment of the shaft '66, assuming 72 to be stationary, the first feed being the normal feed and the last-named a compensating feed.

In the above description, the motions described are relative motions. To make the operation. of the parts entirely clear, the

absolute motions will now be explained, it

being understood that this explanation is given only as illustrative of one way 111 which the Ynechanism operates, since the absolute motions would be varied by a change of friction of the parts, or by placing a different load on the machine. As actually observed, all fecd parts rotate together during the compensating movement. Thus the hand wheel 67 and the parts thereto attached, such as the drive ratchet 68, also the sleeve 72 andthe screw shaft 66 itself, all

rotate clockwise for a limited distance. This action, occurring at the finish of the grind- .ing operation, moves cam 76 on ring 74 a given angular distance beyond the contact position of thumb-screw 78, shaft 66 being turned an equal angular..distance. \Vhen, in repositioning the eccentric feed mechanism so that the grinding wheels 6 can'ente'r a fresh workpiece, the operator has turned the hand wheel 67 far enough in a -countenclockwise direction to bring cam 7 6 to that position where it had just previously caused automatic cessation of grinding bv contact withscrew 78, the parts 67, 67 68 74 and 76 are in the position they occupy .as the wheels 6 leave the lastworkpiece.

And such repositioning has turned shaft 66 counterclockwise,- but only by a limited amount. Such limitedamount is only a small fraction of the previous automatic turning of ratchet 184 and the gear 73 which it controls, said fraction being, of

course, the same as the fraction represented by reducing action of gearing 70, 71, 72

and 73 In order to, hold the ratchet 184 stationary 'at'all times except when it is being moved to effect the said compensation,

we provide a lock member 185fpivoted at 186 (see Fig;

' tional return motion. Therefore when in,

1), said lock member having a pawl teeth -normally pressed Y against the ratchet 184 by a cam plate 187 on the move able pawl lever 181.. i

The resultant of the above is that the 'radius of eccentricity is automatically increased in relation to the position of the hand wheel 67, ring 74 and cam 76 by an amount represented by the given angular.

displacement of ratchet 184 minus the fracthe cycle of grinding of each successive workpiece, the contact points 81 and 82 arebrought into contact by the action of cam plurality of amount as the wheels 6 will have been,

reduced in radius bythedressing operation inaugurated at this time in relation to the radius of the wheels at the completion of the-dressing operation on the last preceding workpiece. I

. As'previous-ly stated, the diamond dressing points 100 must be advanced between successive dressing operations to bring them into position to reduce the wheels at each dressing operationto a radius decreasing in decrements of 'uniformvalue. This is done by advancing the carrying member 129 by means of-the above described compensating mechanism in the following manner: Referring'to Figs. 1 and 3, the member 129 provides a pair of cylindrical rods 188, 188 slida-bly mounted in bearings 189, 189 in the support 2. A screw shaft 190 is also carried by'the member 129 and extends into a casing 191, on the ,inside of support 2, in which a worm wheel 192 is held without end play. The screw shaft 190 wheel 192, the latter being internally threaded. A worm 193 (secs Fig.2) meshes with the worm wheel 192, said worm 193 being fastened on a shaft 194. On the shaft 19%, outside the casing 191, is a ratchet wheel Referring now to Figs. 1 and 10, the ratchet wheel 195 is adapted to be moved by a spring pressed pawl 196 carried by the lever 178, each time the compensating mechanism is actuated, Movement of the ratchet 195 turns the shaft 194 which, by means of the worm 193 turns the worm wheel 192' through a slight angular distance. This moves the screw shaft 190 which moves the passes through the worm member 129 forward in a horizontal plane,

machine with the head 4 above theposition shown inFigs. 1 and 2. Assuming all the adjustable parts are properly set and that the-finished cylinder block has been removed, and an u'nground block 9 fastened to the table 5 by means of the bolts 197 fitting in slots 198 on the hand wheel 67 has been turnedback far enough to allow thewheel unground holes in the new block, the operator throws a switch to places the driving belt on and moves a lever' 199. Said lever 199 is connected to the reversing valve '13, and the head 4 immediately descends. As the head 4 descends, the pin 171, which was above the arm 172, moves said arm downwardly, but this has no effect on the compensating mechanism, merely serving to extend a said.table,,and that the 6 to enter the start the smotors 8, thetight pulley 23 'member 12, whereupon the regular recipro-' catory traverse of the wheels 6 in the workpiece 9 is'inaugurated. Said traverse'con tinues, and the wheels 6 gradually enlarge the'several holes in the workpiece, as the radius of eccentricity is progressively in creased, until bythe feeding movement to increase said eccentricity the cam 76 causes contact between terminals 81 and 82. This,

as already described, causes the head ,4 tolift above its normal working stroke, and causes the dressing diamonds 100 to be moved into the amplified paths of the wheels 6, ,thus dressing and truing the latter at a predetermined plane. The downward movement of the head 4. at the commencement of the grinding operation had caused the arm 155, carried bv block 1 11, to strike a switch arm 157, thus placing the switch member 10% in the position illustrated; on the dressing stroke, the arm 153 on block 141 strikes arm 156 and swings the switch member to the opposite position.

This prevents a repetition of the dress ing stroke, and as during said dressing stroke a cam surface 203, on the latch lever 1 13,

' engages the aim 115 and thus positively returns the valve member 118 to its original position, the fluid exhausts from cylinder 128 under the influence of spring 135 and the dressing diamonds 100 are restored to their original position, out of the path of the wheels .6.

The automatic grinding is now resumed, and'upon a predetermined increase in the radius of eccentricity as measured by the distance the cam 7 6 has to travel from the screw 77 to the screw 78, the contacts 81 and 82 are brought together, whereupon the grinding eases, the head 4 moves upwardly car'- rying the wheels 6 past the dressing diamonds 100, now in inoperative position. Thereupon the compensating mechanism, to change the relation ofthe radius of eccentricity to the position of final contact and also to move the diamond slide 134: forward, is actuated, and the head 4 now comes to rest. This completes the cycle of grinding, which it will benoted, is entirely automatic once the lever 199' is moved to start it.

In the above, it should be noted that it is not absolutely essential to provide a diamond slide 129 to move the diamonds 100 away from the path of the wheels 6. since said grinding wheels partake only of vertical reciprocatory and rotary motion. However, we have shown suchmechanism because the provision thereof prolongs the life of the diamonds 100, which are expensive,- and which, in the absence of means to slide them out of the way-0f the wheels 6 as the head 4 ascends at the finish of the cycle, would be unnecessarily used in truing the wheels at a stage when truing is not required.

In the modified form of the invention, in

which the mechanism is dilferent from that already described as illustrated in Figs. 14 and 15,the same eccentric rotatin and feeding motion is employed, also the llead 4: partakes of the same vertical reciprocatory motion, responsive to actuation of thereversing member 12 by the dogs 10 and 11. In fact the same electric circuits and operating mechanism are used, the difference being that the member 129 which carries the diamond slide 13d is directly attached to the work table 5. The modified form of the invention involves the compensating ofthe eccentric feed, but instead of feeding the diamond carrying member 134 directly forward, it partakes of the increasing eccentric motion of the table 5, and the latter is. locked at'a given position in its eccentric rotary motion when the wheels 6 are to be trued. Thus, in the compensating mechanism shown in Figs. 1 and 10, all the parts are employed exceptthat the pawl 196 and the ratchet wheel 195 thatit operates, and the associated mechanism 0perated by said ratchet, are omitted.

Referring particularly to Figs. Hand 15, the diamond operating pipe 121 is shown, which leads fluid, by a flexible tube 204 to fa port 127 located in the side of a cylinder 128 the same as cylinder 128 already described, Shunted into the line piping 1 21 is'piping 205 which leads the fluid to a port 206 in a cylinder 207. Said cylinder contains a piston208connected to a plunger 209 1 around which is a coil spring 210. The plunger 209 is adapted, when moved, to enter a hole 211' provided in the head 29, I which otherwise is similar to the head 29. 2

Also shunted into the piping 121 is a branch pipe 212 which, as best shown in Fig. 15 leads the fluid to a port 213 in another cylinder 214. Said cylinder 214 contains a,

piston 215 normally pressed to the position shown by a spring 216 and the piston rod 217 of this operatingunit has a belt shifting fork 218 on its outer end. The fork 218 surrounds the driving belt 219, and when the piston moves. thus shifting the fork218 the belt 219' is shifted from the fast pulley 23 to the loose pulley 24. I

The modified mechanism operates in ex; actly the same manner as thefirst form of r the invention described. When the magnet 111 is energized, the pressure fluid moves the diamonds into position and at the same time neously.

looks the headj29 so that the diamonds 100 are stopped in a definite place, their relation to the wheels 6 being determined by the movement of theeccentricfeed mechanism to that point. The head 29 can be readily stopped by the plunger 209, since the belt 219 is shifted to the loose pulley 24:, as described, simultaneously with the moving of the plunger 209, the fluid being admitted to cylinders 207 and 214 practically simulta- In the succeeding cycle of grinding, the wheels 6 will definitely be reduced by the next dressing action, since the compensating .mechanism has increased the radius of ec- Y centricity'at the making of the contacts 81 and 82, as Well as the value of said radius at the making of the final contacts 81 and 82.

. In this form of the invention, it will be noted that the diamonds bear a fixed relation (when moved to their operative positions) to the axes in the holes of the Workpiece 9, and so the wheels 6 are dressed to a definite size in relation to said-axes:consequently the fixed predetermined increase I a of the radius of eccentricity determined by the advance of cam 7 6 from screw 77 to screw common orbit of the workholder and there-- by equally varying each individual orbit,

and a dressing tool for each grinding wheel,

said tools being so arranged that the axes of all the individual orbits are equally spaced in the same direction eachfrom the dressing tool for its grinding wheel whereby, due to the equal variation of radius of all the or-' hits, the relation of all the points of con-- tact of the work with the grinding wheel to the points of engagement of the dressing tools With the grinding wheels will remain each equal to every other, regardless of such variation of radius of the orbit..

2. In a grinding machine, a'plurality of grinding wheels whose axes are parallel and are located'in a common plane, work-holding means adapted to hold work engageable at separate individual places by each of the grinding wheels, means for producingsuch an orbital movement of the workholder as to cause an equal individual orbital movement of each grinding wheel-engaging position of the work aboutits grinding wheel,

and for varying the radius of the common orbit. of the workholder and thereby equally varying each individual orbit, and a dressing tool for each grinding wheel, said tools. being located in a plane parallel to the afore-- said plane of the grinding wheel axes, v whereby the axes of all the individual orbits are equally spaced in the same direction each from the dressing tool for its grinding wheel, whereby due to the equal variation of the radius of all the orbitsthe rela-' tion of all the points of contact of the work with the grinding wheels to the points of engagement of the dressing tools with the grinding wheels will remain each equal to every other regardless of such variation of radius of the orbit. I

3. In a grinding machine,ua plurality of grinding wheels whose axes are parallel. and

are located in a common plane, workhold ing means adapted to hold work engageable at separate individual places by each of the grinding wheels, means for producing such an orbital movement of the workholder as to cause an equal individual orbital movement of each grinding wheel engaging position of the work about its grinding wheel, and for varying the radius of the common orbit of the workholder and thereby equally varying each individual orbit, and a dressing tool for each grindingwheel, said dressing tools being mounted on a common support movable parallel to the plane of the grinding wheel axes and also movable. at right angles thereto, one motion serving to simultaneously advance each of the dressing tools towards, a grinding wheel on a line of a radius of the latter, and. the other move I ment carrying every dressing tool laterally of said radius into and out of operativerelation to said grinding wheel.

4. In a grinding machine a plurality pf grinding wheels whose axes are arallel,

Workholding means adapted to hold work engageable at separate individual places by each of the grinding wheels, means for producing such an orbital movement of the V --workholder as to cause an equal individual i orbital movement of each grinder-engagii'ig position of the work' about its grinding Wheel, and for varying the radius of thecommon orbit of the workholder and thereby equally varying each individual orbit, and a dressing tool for each grinding wheel" carried by said workholder, said tools being equally spaced in the same direction from the several grinding wheels at any position in the orbital movement, and means for stop ping the orbital movement of the workholder in such aposition that the grinder engaging. position of each workpiece is in line with the dressing tool.

- Dated this 8th day' of February, 1927.

RICHARD A. HEALD. WALDO'J, GUILD. 

